For 16gb I have installed it and selected 1866 under the bios I was getting random bsod make a long story short I tried everything to get it to work I get bsod on all settings except for when I put m.b. in auto which runs the ram at 1333mhz.

By the way m.b. has the latest bios and I am running win7 64 bit. To top it off I bought the ram through newegg and only had a 30 days to return, it is just past the 30 days so now I can not return to get my money back. It took me that long to figure out it was the ram that was causing my bsod problems. One more item I never increased any voltages or anything just tried manually to put ram at the rated speed 1866 or even 1600 and yes I even tried x.m.p. all give me random bsod unless as I stated I put ram setting on auto it runs 1333 and I have 0 problems then.

Re: asus p9x79 pro only runs my ram at 1333mhz

OK I might have just found something your web page says it is "DDR3 PC3-14900 • 9-9-9-27 • Unbuffered • NON-ECC • DDR3-1866 • 1.5V • 512Meg x 64". But in the motherboard manual it says the "motherboard does not support dimms made up of 512mb (64mb) chips or less". Chapter 2. Page 2-6. Although your page states "Guaranteed-compatible with the ASUS P9X79 PRO" I'm not a memory expert but is the ram not the same thing the book says it will not support?

Re: asus p9x79 pro only runs my ram at 1333mhz

HI, please try just one stick and see if you can set it to 1600 to run. The point is to see if either stick is behaving differently than the other. So after trying the first, try the other.

Also, please be sure that you have the sticks in the proper two slots. I don't know what the config for your mobo is, but in mine. I have to use slots' A2 and B2 and they're not color coded.

So, again, we're trying to break it all down to a single stick OR RAM slot. Therefore, if the RAM stick works correctly in one slot, then try the same stick in the other, then do it all over again for the 2nd stick and slots.

That should give you a starting point. Report that info and then see if a more knowledgeable person can throw their ideas/thoughts in.Rich

Re: asus p9x79 pro only runs my ram at 1333mhz

I have 4 sticks in total and yes they are in the correct slots. I guess I could try to switch slots but in light of what it says in motherboard manual (read my second post) it sounds like its incompatible to begin with.

Re: asus p9x79 pro only runs my ram at 1333mhz

OK I did call and they suggested I use one stick at a time and run memory tester on each stick he thinks I might have 1bad stick. But do I test with my system set at 1866 or what the motherboard picks it up as 1333? Or use the xmp setting? And what program should I use to test with? Memtest86?

Re: asus p9x79 pro only runs my ram at 1333mhz

Yes, as I said, running one stick at a time was the next best procedure. I have to say that the fact you've got any errors at all at the 1866 speed bothers me.

I use memtest86 and the procedure that you've outlined was correctly done. But what do you mean in step four of the procedure when you said "blue slots"?

If I understood you correctly in that procedure you did take each stick, one at a time, and place them in each slot of the motherboard replaying the test for each slot of that single stick.

Then you took the second stick and repeated that procedure, followed by the third and then the fourth. At least, that's what you should've done first at 1333, (only because you can use that speed is a comparative), and then it 1866.

But going back to what I said at the beginning, getting any errors at all, and especially at the speed rated as default, does not sound good. If you go to memtest86's website/forum, they may be able to tell you exactly what test 6 is saying.

Your other option is to consider the motherboard as a possible problem. It should be a dual channel motherboard in order to work with that RAM or at least work with all four sticks in dual channel mode. But I'm beginning to suspect the RAM because of those errors.

Somebody on this website should know what is going on here but I haven't seen anybody throw in. I've got leave for a few hours this morning but hopefully somebody in memtest86's forum may have an answer.

Re: asus p9x79 pro only runs my ram at 1333mhz

I have 8 ram sockets 4 are blue and 4 are beige it is recomended in the mother board manual to always use the blue sockets first. I did not test anything in the beige sockets. Yes after I tested each individual stick in a single socket and they all tested good I thought maybe there was a bad socket, so to test the sockets I tested them one at a time with a single stick and no errors were reported. Hope that clarifies what I did. I guess I'll call crucial again.